Biography of DW Stewart, author of 'Old and Rare Scottish Tartans' (1893)

[Stewart of Galloway]

I am searching for a biography of DW Stewart (father of DC Stewart (Scotland's Forged Tartans) who wrote 'Old and Rare Scottish Tartan's' (1893).
I read a bio a few months ago but just cannot find it again either online or in my collection of books.
What I recall is that DW Stewart worked for a tartan producer in Scotland and after his book was published his business went badly. I recall that he left his wife and children or his wife left him and he subsequently emigrated to Australia. So I am keen as an Australian to try and track down what happened to him once he came here and whether there's any descendants or evidence of him still around. Any help would be appreciated.